1. Field of the Invention
The present invention relates to an optical imaging apparatus which irradiates low-coherence light onto a subject and constructs a cross-section image of the subject based on information from the light scattered at the subject.
2. Description of the Related Art
In recent years, an interference-type OCT (optical coherence tomography) apparatus capable of obtaining cross-sectional images of a subject using low-coherence light has been proposed as an apparatus capable of obtaining optical information within tissue of an organism being diagnosed, such as disclosed in WO92/19930 (U.S. Pat. No. 5,321,501), for example.
This WO92/19930 discloses a probe provided with a rotating tube provided with an optical element and optical element inside an outer tube-shaped sheath for insertion into the body cavity. However, no probe detaching means is provided, so scrubbing and sterilization necessary for use in the body cavity cannot be performed. Also, the optical element such as the prism at the tip end is exposed from the external sheath and rotates in that state, so there is the possibility that the organism may be damaged.
Also, Japanese Unexamined Patent Publication No.11-148897 discloses an optical probe for OCT wherein the optical probe portion and the observation apparatus portion are detachable. A detachable connector portion is provided, and the optical element such as the prism at the tip end is covered and sealed with a transparent sheath.
However, according to this art, rotational force is not transmitted smoothly unless the rotational shaft of the rotation transmitting means for rotating the rotating tube provided within the connector portion of the optical probe, and the rotational shaft of the rotation driving means provided in the observation apparatus are precisely matched, resulting in irregularities and instability in the rotating speed, but in practice, it is difficult to match the two rotational shafts in a precise manner.
Further, the rotation transmitting means at the base portion of the rotating tube and the optical fiber connecting member are formed integrally, so in the event that any inclination occurs between the two, or in the event that slack occurs in the bearing supporting the rotating shafts so as to move in the direction of the fiber, the connection of the optical fiber of the optical probe and the optical fiber of the observation apparatus becomes unstable, which has been a problem.
Particularly, in the case of the single mode fiber used for OCT, there is the need to abut the fiber cores at a precision in the order of several μm, so even slight shifting or a slight gap at the fiber ends results in massive loss of light, deterioration in the observation S/N ratio, and irregularities in the intensity of the observed image due to change in the connection state owing to rotation.